DBにデータが保存されません

Question

○解決したい事
mysqlのmaterialsテーブル、recipi_materialsテーブルにデータを保存したいです。
現在、recipisテーブルにはデータ保存がされておりますが、上記２つのテーブルには全くデータが反映されていない状態です。

recipis controller.rb

class RecipisController < ApplicationController
    def index
        @recipi = Recipi.all.order("DESC")
    end

    def new
        @recipi = Recipi.new
        @recipi.materials.build
    end

    def create
        @recipi = Recipi.new(recipi_params)
        @recipi.save
        redirect_to"/"
    end


    private
      def recipi_params
        params.require(:recipi).permit(:image, :title, :content, :content_image, materials_attributes: [:id, :materials, :quantity]).merge(user_id: current_user.id)
      end
end

new.html.haml

= form_with model: @recipi, local:true do |f|
  
  .post
    %h1
      レシピを投稿して下さい！

  .post_recipi
    .post_recipi-left
      .post_recipi-left_title
        .post_recipi-left_title-subject
          レシピのタイトル
        =f.text_field :title, placeholder:"タイトルを入力して下さい", class:"recipi__title"
      .post_recipi-image
        =f.label :content_image, class:"label_image"
        =f.file_field :content_image, class:"image_field"
        =f.hidden_field :image_cache
      .post_recipi-content
        =f.text_area :content

    .post_recipi-contents
      .recipi_items-main
        .recipi_items-main_subject
          材料名を入力して下さい(豚バラ肉など)
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
        =f.text_field :materials, class:"recipi_items-materials",value:""
      .recipi_items-quantity
        .recipi_items-quantity_subject
          分量を入力して下さい(大さじ1、100gなど)
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
        =f.text_field :quantity, class:"recipi_items-quantity_content"
    .submit
      =f.submit :"送信"

materials.rb(モデル)

class Material < ApplicationRecord
    has_many :recipi_materials
    has_many :recipis, through: :recipi_materials
end

recipi.rb(モデル)

class Recipi < ApplicationRecord
    belongs_to :user
    has_many :recipi_materials
    has_many :materials, through: :recipi_materials
    accepts_nested_attributes_for :materials

    mount_uploader :image, ImageUploader
end

recipi_material.rb(モデル)

class RecipiMaterial < ApplicationRecord
    belongs_to :recipi
    belongs_to :material
end

追記

その後、recipiモデル、materialモデルに、optional:trueを付属させてみましたが、状況に変化なしです。
初心者で、おかしな文法を使用しているかもしれませんが、何卒ご教授の程宜しくお願い致します。